I have a problem with my A/C... when I hit the gas, the air blows to the defrost.... I assume vac leak... the question is, where do I start looking? is there a most common area(s) to look at first? thanks!
i had thisproblem with my trans am once, sounds alot like your friends when passing someone or just getting over about 1/2 throttle the a/c would switch immediately from the vents to the defroster turn out to be the vacuum resevoir ( ball ) had a crack in it after GM replaced it a/c never did it again